<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        #d3{color:red;}
        .c1{color:green;}
        h3{color:yellow;}
        h3,#d3,h2{background-color: pink}
        /*任意元素选择器*/
        *{
            /*边框：粗细 样式 颜色*/
            border: 1px solid red;
        }
        /*属性选择器*/
        input[type='text']{
            background-color: mediumpurple;
        }
    </style>

</head>
<body>
<input type="text"><input type="password">
<div class="c1">刘德华</div><div>张学友</div><div id="d3">郭富城</div>
<span class="c1">苹果</span><span>香蕉</span><span>橙子</span>
<h2>电视</h2><h2 class="c1">手机</h2>
<h3>空调</h3>
</body>
</html>